A
number of Bon Temps residents (including Holly & Arlene) have been
kidnapped by a roving band of Hep-V infected vampires, and are being held
in a basement under Fangtasia, where the vamps are feeding on (and
killing) them.

In this scene, Bill and Andy are out searching for the victims.

They stop at a large warehouse.

Andy says that the place shut down a year ago, but that they used to find kids partying there all the time.

They roll up the large door and go inside, flashlights ablaze.

They spot a bloody cot, and Bill remarks that the vampires have been nesting there.

Then they enter a larger room and Andy is horrified to see the bodies
of several dead women hung upside-down from the ceiling, their throats
torn out.

Just then, they encounter a small group of vigilante townspeople, who get the drop on them.

Bill lies and says that Andy stayed away from the bar in protest, so the vigilantes will trust him.

Andy pretends that he wants to be the one to kill Bill, but once he has
the gun, he turns it on the others and forces them to leave.

The
location:The Warehouse Vampire Nest

Q.
What is it actually, in real life?

A.An actual warehouse, but nowhere near Louisiana.

Q.
Where can I find it in real life?

A.This warehouse is about where you'd expect to find it: in L.A.'s warehouse district.
It's located at 1327 Palmetto Street, on the northeast side of downtown Los Angeles., at the northwest corner of Palmetto and Santa Fe Ave.
This one is easy to spot - it reads "ACME Wiping Materials Co." across its front. The door that they open is the one with a sign reading "Receiving Department" above it.
Hollywood does a surprising amount of film-making in this warehouse
district; so much so that a surprising number of the old buildings have
signs posted reading "Filming location for rent". (Not long
before they filmed this scene, the 2014 movie "Walk of Shame" was
filming in the same area.)

[ Warning: this isn't the safest part of town. It's often deserted, and it's far
too close to the heart of Skid Row. So exercise reasonable caution. ]

And here is a photo of the warehhouse from True Blood fan Jay B.:

Q.
How the heck did you figure out where it was?

A. While
tracking down locations over the years, I've spent a lot of time in the
warehouse district, since they often film there. While many of the
industrial buildings there are faceless old structures, a few stand
out. Some of them, like this one, still bear a sign painted on
front.

This one reads "ACME Wiping Materials Co.",
a memorable name, which can be seen if you slow down the scene where
the police car pulls up to the warehouse. So it wasn't hard to
find.